Static electricity IEC 80079-36 vs. IEC 60079-0

[Fran67]

Hello everybody,

I work on a machine installed in zone 2 IIC (IECEx), composed of some painted non-electrical components. (supports, baseplate..etc)

There is in IEC 80079-36, 60079-0 and 60079-32-1 some requirements about painting thickness and/or surface requirements to prevent static discharge:
1) I wonder if these requirements have to be applied:
- when a significant charge accumulation mechanism has been identified only? (friction between two insulated components, liquid stream...etc)
or
- in all cases even if the charge accumulation can be generated by non-significant mechanism as ambient dry air, wind...etc?
In other words, do you consider the effects of dry air / wind in your risk assessment (especially for Zone 2)?

2) I dont't understand why there is a difference between max allowable insulated/painted surface for EPL Gc (IIC) in the tables from IEC60079-0 and IEC80079-36:
- 10 000mm² max acc. to 60079-0 table 7
- no restriction acc. to 80079-36 table 8, info that we could understand as "no insulation or painting restriction in zone 2 IIC"
It is a mistake?

Could you please share your experience about this subject to compare my doubts and risk assessment hypothesis with yours on this topic?

Thank You
F

 

[Gr8blu]

ISO/IEC 80079-36 specifies the basic methods and requirements for design, construction, testing and marking of non-electrical Ex equipment, Ex Components, protective systems, devices and assemblies of these products that have their own potential ignition sources and are intended for use in explosive atmospheres.

IEC TS 60079-32-1:2013+A1:2017 gives guidance about the equipment, product and process properties necessary to avoid ignition and electrostatic shock hazards arising from static electricity as well as the operational requirements needed to ensure safe use of the equipment, product or process.

IEC 60079-0:2017 specifies the general requirements for construction, testing and marking of Ex Equipment and Ex Components intended for use in explosive atmospheres.

There is a calculation method to determine the "energy" resulting from a static charge. If the "energy" level is sufficient to ignite the flammable/ignitable medium, it is considered a hazard. To be conservative, one could ALWAYS choose the anti-static approach to eliminate discharge between surfaces.

The difference between the limit from 60079-0 (electrical components) and 80079-36 (non-electrical components) is that the latter does not have to consider electrical arc distance.

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